Sealing device for rotary piston engine



Sept 6 1955 KENlcHl YAMAMoTo 3,270,954

SEALING DEVICE FOR ROTARY PISTON ENGINE Filed Feb. lO, 1965 FIG 2 l INVENTOR l y l I3 ATToNEYs United States Patent C 3,270 954 SEALING DEVICE FOR RTARY PISTON ENGINE Kenichi Yamamoto, Hiroshima-shi, Japan, assigner to Toyo Kogyo Company Limited, Hiroshima-ken, Japan Filed Feb. 10, 1965, Ser. No. 431,639 Claims priority, application Japan, Feb. 17, 1964, 39/10,973 3 Claims. (Cl. 230-145) The present invention relates to -a sealing device for a rotary piston internal combustion engine and particularly to a sealing device `for providing a seal between the apex of a polygonally shaped rotor which rotates within an annular 'casing and .the casing.

Generally, in a rotary piston internal combustion engine, a polygonally shaped rotor is eccentrically mounted Within an annular casing having a trochoidalshaped internal peripheral Wall, and crescent shaped chambers are defined between the rotor and the annular casing which vary in volume, increasing and then decreasing during the eccentric rotational displacement of the rotor within the annular casing as the apexes of the rotor move along the internal face of the casing. During this action the intake and compression of the gas prior to liring it within the chambers and exhaust of the products of .the combustion are performed. To seal the chambers separated by the polygonal rotor within the casing tightly, it has been suggested that there be instal-led an alpex seal piece slidable radially within an axial groove provided at each apex of the polygon-al rotor Iso that the seal piece is forced l'against the internal face of the annular casing by centrifugal force and slides along the internal peripheral wall of the annular casing during the rotational movement of the rotor during operation of the engine.

An engine having ksuch a lsealing device has been proved to be subject to abnormal wear on the internal trochoidal face of the annular casing and early deterioration of the sealing effect between the apex seal and the internal facefof the casing occurred.

In finding a ysolution to the problem of overcoming this defect, the factors of mass, rigidity, vibration and shock damping effect of the seal piece must be considered. That is, the Ifrictional force between the apex seal piece and the internal face of the annular casing, on which the seal piece slides -under the effect of centrifugal force, increases with the increase of the rotational speed of the rotor, and also increases with an increase in the mass of the `seal piece. I-n View of this problem, the apex seal piece should have a mass to prevent a large increase in the `,frictional force between the seal piece and the casing with an increase i-n rotational speed. However, the apex seal piece itself, on the other hand, must be wear-resistant, rigid and large enough in size and in external `shape `so as to be radially slidably held within the groove on the .apex of lthe rotor. It is therefore impossible by 'simply altering the material of the seal piece to enable the apex Iseal to satisfy lal1 of the above requirements, because reducing the mass of the seal piece, regardless of what kind of material is used, inevitably results in making the apex seal smaller in size, and a seal piece of low density material is defective with respect to rigidity and wear resistance. Also, the seal piece is affected by irregular vibration `and shock during operation of the engine and the inertia force of the seal piece due to such irregular vibration and shock causes irregular frictional contact between the seal piece and the internal annular Wall of the casing and results in abnormal wear on the internal face of the annular casing.

It is an object of the invention to provide an improved apex seal device for a rotary piston internal combustion rice engine which is Ismall in mass, has excellent wear resistivity, rigidity and damping effect with respect to vibration and shock.

The objects and advantages of Ithe invention will be understood from the yfollowing description taken together with the accompanying drawings, in which:

FIG. 1 is la cross sectional view of a rotary piston engine showing a rotor provided with apex seal devices;

FIG. 2 is 1a side view of an apex seal piece partially in section and on an enlarged scale;

FIG. 3 is a bottom view of the alpex seal piece of FIG. 2;

FIG. 4 is an end view of the apex seal piece of FIG. 2; 4and FIG. 5 is a side view similar to FIG. 2 showing a modified form of the seal piece.

Referring to rthe drawings, a triangular rotor 1 is eccentrically rotatably mounted on a crankshaft 2 within an Iannular casing 3 having a .trochoidal shaped internal peripheral wall 4. At each .apex 5 of the rotor 1 is a y longitudinal groove 6 extending the entire axial length of the rotor, and Within the groove is radially slidably mounted Ian `apex 'seal piece 7 having a substantially rectangular cross-section and an appropriate length. Said alpex 'seal can be of a material 'such as a special cast-iron group which is Isufliciently strong when subjected to severe heat `and pressure of la gas explosion. Within the yapex seal piece body are longitudinal holes 8 extending throughout the entire length thereof, one of which holes is in the radially outer portion so as to leave a sliding contact portion 9 of suliicient thickness for withstanding the sliding frictionall force between the seal piece and the internal wall of the `annular casing. Another one of the holes 8 is in the radially inner portion so as to leave an intermediate wall portion 10 between `the upper and lower holes 8. Below the lower hole 8 is a bottom portion 11. The lpo'sition of the intermediate wall portion 10 will be determined by the depth of the groove 6 and :the depth `of the groove 6 should be such that said wall portion 10 will be at a position where the upper edlge portion 12 of the groove 6 is located. Extending vertically through .the intennediate wall portion 10 and the bottom portion 11 in a radial direction with respect to the piston lare cross holes 13 substantially parallel to each other Iand at :proper intervals, so as to form bridges 14 which are integral with the seal piece body and disposed yat proper intervals within the thus hollowed out seal piece body.

According to .the present invention, the apex seal piece having an external size sutiicient to be slidably mounted Within the `groove 6 so as to form a seal between the internal Wall face 4 of the -annular casing and the rotor apex 5, h-as its mass reduced by the longitudinal and cross holes 8 and 13 which intersect within the seal piece body. This prevents intensive wear on the internal Wall 4 of the annular casing 3 because centrifugal force faecting the iseal piece 7 during rotation of the rotor 1 and the frictional force between the 'sliding contact portion 9` of the seal piece and the internal wall face of the annular casing 3 are decreased due to the reduced mass of the seal piece 7. A decrease of the inertia of the seal piece is yalso accomplished by reducing the mass thereof by providing the intersecting holes 8 and 13, so that irregular vibration Iand shock of the seal piece which `are caused by irregular vibration land shock of the rotor 1 during operation of the `eng-ine and which act on the seal piece 7 to cause irregular heavy frictional contact of the seal piece with the internal wall face ofthe annular casing 3 are damped, Iand abnormal uneven wear on the inner wall face of the casing 3 is prevented.

During operation of the engine, the apex seal piece 7 slides in the radial direction within the groove 6 under the effect of centrifugal force and a pressing force is exerted on one side of the body by the wall of the groove 6 in the revolving rotor 1. To withstand this force, the hollowed out seal piece 7 has its internal strength increased by the bridges 14 which are integral with the seal piece body and disposed within the hollow seal piece body at proper intervals.

FIG. shows a modified form of the seal piece in which there is only one longitudinal hole 8 which is positioned above, or radially outwardly of, the position of the upper edge of the groove 6. The solid bottom portion 11 below the longitudinal hole 8 has a radial dimension which substantially corresponds with the depth of the groove 6 so that the portion of the seal piece held by the groove 6 is sufliciently strong and rigid to Withstand the force of the groove wall during operation of the engine. In this modified form a vertical or radially extending cross hole 13 can be positioned in an appropriate middle portion and intersect with the longitudinal hole 8.

It is thought that the invention and its advantages will be understood from the foregoing description and it is apparent that various changes may be made in the form, construction and arrangement of the parts without departing from the spirit and scope of the invention or sacrificing its material advantages, the forms hereinbefore described and illustrated in the drawings being merely preferred embodiments thereof.

What is claimed is:

1. A rotor and sealing device for a rotary piston internal combustion engine having an annular casing with a trochoidal shaped internal peripheral wall and a crankshaft within said casing for eccentrically rotating a rotor within said casing, comprising a triangular rotor adapted to be eccentrically rotatably mounted on the crankshaft for rotation within the annular casing, said rotor having an axially extending groove at each apex thereof, an apex seal piece radially slidably mounted in each groove, each apex seal piece having at least one longitudinally extending bore therethrough adjacent the radially outward edge of the seal piece and leaving between said bore and the radially outward edge a frictional sliding contact portion of sufficient thickness for withstanding the sliding frictional forces of the seal piece on the internal wall of the casing, said bore being entirely within the portion of the seal piece which projects out of the groove with the edge of the groove at a position on the seal piece `radially inwardly of the said at least one bore, and at least one radially extending hole in said seal piece extending from the edge thereof within the groove into said bore and positioned substantially midway of the length of the seal piece.

2. A rotor and sealing device for a rotary piston internal combustion engine having an annular casing with a trochoidal shaped internal peripheral wall and a crankshaft within said casing for eccentrically rotating a rotor within said casing, comprising a triangular rotor adapted to be eccentrically rotatably mounted on the crankshaft for rotation within the annular casing, said rotor having an axially extending Igroove at each apex thereof, an apex seal piece radially slidably mounted in each groove,

each apex seal piece having a pair of longitudinally extending bores therethrough, one adjacent the radially outward edge of the seal piece and leaving between said one bore and the radially outward edge a frictional sliding contact portion of sufficient thickness for withstanding the sliding frictional forces of the seal piece on the nternal wall of the casing, said one bore being entirely within the portion of the sealpiece which projects out of the groove, and the other bore being parallel to said one bore and being adjacent the radially inward edge of the seal piece and leaving between said other bore and said radially inward edge a bottom portion and leav- 'mg between said two bores an intermediate wall portion, said other bore being entirely within the portion yof the seal piece within the groove, with the edge of the groove at a position on the seal piece adjacent said intermediate wall portion of the said bores, and a plurality of radially extending holes in said seal piece extending from the edge thereof within the groove through said other bore and into said one bore and spaced at substantially equal intervals along the length of said seal piece.

3. A rotor and sealing device for a rotary piston internal combustion engine having an annular casing with a trochoidal shaped internal peripheral wall and a crankshaft within said casing for eccentrically rotating a rotor within said casing, comprising a triangular rotor adapted to be eccentrically rotatably mounted on the crankshaft for rotation within the annular casing, said rotor having an axially extending groove at each apex thereof, an apex seal piece radially slidably mounted in each groove, each apex seal piece having a single longitudinally extending bore therethrough adjacent the radially outwardl edge of the seal piece and leaving between said bore and the radially outward edge a frictional sliding Contact portion of sufficient thickness for withstanding the sliding frictional Vforces of the seal piece on the internal wall of the casing, said bore being entirely within the portion of the seal piece which projects out of the groove with the edge of the groove at a position on the seal piece radially inwardly of the said bore, and a single radially extending hole in said seal piece extending from the edge thereof within the groove into said bore and positioned substantially midway of the length of the seal piece.

References Cited by the Examiner UNITED STATES PATENTS 1,114,046 10/1914 Roessler 230-153 1,805,063 5/1931 Wrona 103-136 2,070,662 2/1937 Johnson 230-153 2,305,317 12/1942 Nickell 230-207 2,423,639 7/1947 Czarnecki 123--8 2,902,980 9/1959 Barrett 123-8 3,180,564 4/1965 Fuhrmann et al. 123-8 3,185,387 5/ 1965 Paschke 230-145 FOREIGN PATENTS 409,669 2/ 1910 France.

MARK NEWMAN, IPrimary Examiner.

W. I. GOODLIN, Assistant Examiner. 

1. A ROTOR AND SEALING DEVICE FOR ROTARY PISTON INTERNAL COMBUSTION ENGINE HAVING AN ANNULAR CASING WITH A TROCHOIDAL SHAPED INTERNAL PERIPHERAL WALL AND A CRANKSHAFT WITHIN SAID CASING FOR ECCENTRICALLY ROTATING A ROTOR WITHIN SAID CASING, COMPRISING A TRIANGULAR ROTOR ADAPTED TO BE ECCENTRICALLY ROTATABLY MOUNTED ON THE CRANKSHAFT FOR ROTATION WITHIN THE ANNULAR CASING, SAID ROTOR HAVING AN AXIALLY EXTENDING GROOVE AT EACH APEX THEREOF, AN APEX SEAL PIECE RADIALLY SLIDABLY MOUNTED IN EACH GROOVE, EACH APEX SEAL PIECE HAVING AT LEAST ONE LONGITUDINALLY EXTENDING BORE THERETHROUGH ADJACENT THE RADIALLY OUTWARD EDGE OF THE SEAL PIECE AND LEAVING BETWEEN SAID BORE AND THE RADIALLY OUTWARD EDGE A FRICTIONAL SLIDING CONTACT PORTION OF SUFFICIENT THICKNESS FOR WITHSTANDING THE SLIDING FRICTIONAL FORCES OF THE SEAL PIECE ON THE INTERNAL WALL OF 